Field of the Invention
The present invention relates to a sliding member, a sliding member for a fixing device, a fixing device, an image formation apparatus, and a method for producing a sliding member.
Description of the Related Art
Japanese Laid-Open Patent Publication No. 08-262903 discloses a fixing device with which an image formation apparatus of an electrophotography system, such as a printer, a copier, and a facsimile is equipped. This fixing device has a pressurizing and fixing roll, an endless belt in contact with this pressurizing and fixing roll, and a pressing member which is disposed inside this endless belt and presses an inner circumferential surface of the endless belt toward the pressurizing and fixing roll. This type of fixing device allows the roll and the belt to be pressed into contact with each other to form a fixing nip, and accordingly, it is referred to as a belt nip fixing system and is considered to be advantageous in that it is excellently energy-saving, light-weight, compact and inexpensive.
Japanese Laid-Open Patent Publication No. 2004-206105 discloses a fixing device of a configuration in which a sheet-like sliding member sliding on an inner circumferential surface of a pressurizing belt is provided to a pressing member and a lubricant is interposed between this sheet-like sliding member and the inner circumferential surface of the pressurizing belt. This fixing device can have between the inner circumferential surface of the pressurizing belt and the pressing member a sliding resistance reduced by the lubricant and thus allows the pressurizing belt to be smoothly, circularly moved together with a fixing roll. As the lubricant, silicone oil, amino modified silicone oil, methylphenyl silicone oil, etc. are used. Furthermore, as the sheet-like sliding member, a glass cloth or the like impregnated with fluororesin and sintered is used. A fluororesin containing, sheet-like sliding member is also disclosed in Japanese Laid-Open Patent Publication Nos. 10-213984 and 2001-249558.
Japanese Laid-Open Patent Publication No. 2009-069400 describes as a lubricant holding member equivalent to the above sheet-like sliding member an example using a mesh sheet of aramid fiber.
However, silicone oil degrades through thermal oxidation. For example, when the fixing device is continuously operated for a long period of time, the pressurizing belt's rotation torque when the belt circularly rotates increases. The increase of the rotation torque occurs because the sliding resistance of the pressurizing belt and the sheet-like sliding member increases as the silicone oil's viscosity increases. Furthermore, a phenomenon is observed in which the silicone oil leaks from the pressurizing belt's widthwise opposite ends (or the belt's ends in the direction of the rotation axis) and the silicone oil adheres to a surface of the pressurizing belt. This phenomenon is also considered to be attributed to the silicone oil's degradation based on continuous operation over long time. It is believed that silicone oil is thermal oxidized and degraded because as temperature increases to be high, a radical is generated and subsequently, the silicone oil crosslinks between molecules and thus gelates.
Accordingly, when using silicone oil as a lubricant for a fixing device, the silicone oil is degraded by long-term use, which causes inconvenience, such as an increased torque when circularly rotating the pressurizing belt, leakage of the lubricant toward an outer circumferential surface of the pressurizing belt, and the like. Furthermore, when the lubricant leaks, the lubricant between the sliding member and the inner circumferential surface of the pressurizing belt becomes insufficient, and the sliding member and the pressurizing belt are increasingly abraded, which leads to a failure of the fixing device.